We have already seen how the Altar represents our Lord; this explains why it is treated with so much honour; the rest of the Church represents the members of the Mystical Body of which Christ is the Head, that is to say, the Faithful of whose aggregate Holy Church, the Bride of Christ, is composed. On first going up to the Altar, the Priest has already incensed it in every direction, thus paying homage to Christ Himself. Now again, this ceremony is performed with sacred pageantry; just as the Eastern Kings laid their rich gifts at the Feet of the Divine Infant, as the Gospel tells us, so too is the Priest about to burn incense, in his turn, as a homage to his Master and his King.
But, another ceremony must precede that of the incensing of the Altar itself. This Bread and Wine just offered by the Priest have been raised above the order of common things by this very offering made of them, so much so indeed, that were the Priest to die at this moment of the Function, this Bread and Wine must be disposed of in the Piscina. To show her reverence for them, Holy Church sheds on them the perfume of her incense, as if she were doing so to Christ himself. This custom of using perfumes in Church ceremonies began in the East, where they can be procured in rich abundance. But in our cold countries though it is much more difficult to get them, Holy Church will not allow our ceremonies to be utterly deprived of them, and so she prescribes the use at least of Incense, just as for the Chrism, she will at least have Balsam mixed with the Oil. After the incensing of the Bread and Wine, incensatio super oblata, the Altar itself is honoured in like manner. Before making use of the incense, it must be blessed; the Priest does so by the following Prayer: Per intercessionem beati Michaelis Archangeli stantis a dextris altaris incensi ... The angel who holds the golden Thurible in the Apocalypse is not named. Holy Church here names Saint Michael, Prince of the Heavenly hosts. Some have thought that there is an error in this passage, because in Saint Luke, the Angel Gabriel is named standing at the Right of the Altar; but Holy Church pays no heed to these their objections; St. Luke does not say that Gabriel held a golden Thurible. The first blessing of the Incense was less solemn; the Priest then only said: Ab illo benedicaris in cujus honore cremaberis. Mayst thou be blessed by Him in honour of whom thou art to be burned. But in this place, the Angels are called upon because the Mystery of Incense is no other than the Prayer of the Saints presented to God, by the Angels, as St. John tells us, in His Apocalypse (viii. 4): The smoke of the Incense ascends as does the Prayer of the Saints before the Throne of God: Et ascendit fumus incensorum de orationibus sanctorum de manu Angeli coram Deo.
The Priest incenses the Bread and Wine in such a way, that its odour may perfume, and wholly cloud in fragrance the Things offered; while so doing, he says these words: Incensum istud a te benedictum, ascendat ad Te Domine, et descendat super nos misericordia tua. May this incense, O blessed by Thee, ascend to Thee, O Lord, and may Thy Mercy descend upon us. This Prayer, whilst being a homage paid to God, is a wish expressed for ourselves also. The Priest divides these words, at intervals, whilst incensing at several parts to be thus honoured, in performing which ceremony, he follows what the rubrics prescribe. When he first incensed the Altar, the Priest said no Prayer; but now, when thus honouring it a second time, Holy Church bids him repeat a portion of Psalm cxl., which she selects, chiefly on account of these words which occur therein, and which are the first she puts on the lips of the Priest: Dirigatur, Domine, oratio mea sicut incensum in conspectu tuo. May my prayer, O Lord, ascend as incense in Thy sight. It is thus she always does, ever selecting with wonderful appropriateness whatsoever suits the circumstance, whether in Psalms, or in Gospels and Epistles. The Priest begins by incensing the Cross, or the Most Holy Sacrament if exposed; he then bows before the Cross, or genuflects, if the Most Holy Sacrament is reserved in the Tabernacle of that Altar; then, if there be relics there exposed, he incenses them with two throws of the Thurible, first on the Gospel side, then on the Epistle side; after which he incenses every part of the Altar. In all other respects, this incensing differs in no way front the first, nor from that which is performed at Lands and Vespers.
On returning the Thurible to the Deacon, the Priest gives expression to a good wish in his regard as well as in his own, saying: Accendat in nobis Dominus ignem sui amoris et flammam aeternae charitatis. May the Lord enkindle in its the fire of His Love and the flame of everlasting charity. On taking the Thurible, the Deacon kisses the Priest’s hand, and then the top of the chains; he does the contrary, on presenting it. These customs have come to us from the East, and, inasmuch as they are marks of reverence and respect, it is to the Liturgy we owe the preservation of them. The Deacon then honours the Priest with incense, who receives it standing sideways to the Altar; but if the Most Holy Sacrament be exposed, as, for instance, at the Mass of Reposition, the Priest comes down from the Altar, and with his face turned to the people, he receives the said honours from the Deacon, who likewise suits his position to the occasion. Then follows the incensing of the Choir, beginning with the Bishop, if present; next the Prelates, if there then the Priests and Clerics; and, finally, all the Faithful, to show that all form but one Body, of whom Jesus Christ is the Head. All, whether Bishops, Prelates, or simple Faithful, should rise on receiving the incense; the Pope alone remains seated for its reception.